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FastLED Python Code Investigation

ci/util/scrapers/fastled_python_investigation.md

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FastLED Python Code Investigation

Overview

This document summarizes the investigation of existing Python code in the FastLED project, particularly focusing on Playwright integration and web scraping capabilities for the FastLED online tool.

Location: All scripts are located in the ci/ci/scrapers/ directory, organized within the CI infrastructure alongside the existing testing infrastructure, including the original Playwright implementation in ci/wasm_test.py.

Existing Python Infrastructure

Dependencies (pyproject.toml)

The project already includes comprehensive dependencies for development and testing:

  • Playwright: playwright - for browser automation
  • Testing: pytest, pytest-xdist for parallel testing
  • FastLED: fastled>=1.2.26 - the FastLED Python package
  • FastLED WASM: fastled-wasm - WebAssembly support
  • HTTP Client: httpx - for HTTP requests
  • Build Tools: uv, ziglang, ninja
  • Code Quality: ruff, mypy, pyright, clang-format, isort, black

Existing Playwright Implementation (ci/wasm_test.py)

The project already has a sophisticated Playwright setup that:

  1. Automatic Browser Installation:

    python
    def install_playwright_browsers():
    os.system(f"{sys.executable} -m playwright install chromium")

  2. FastLED WASM Testing:

    • Starts an HTTP server for WASM examples
    • Tests browser automation with the FastLED.js library
    • Monitors FastLED_onFrame callback execution
    • Validates WebGL/WASM functionality

  3. Error Handling:

    • Console log monitoring for errors
    • Timeout handling for page loads
    • Proper server cleanup

MCP Server Integration (mcp_server.py)

The project includes a comprehensive MCP (Model Context Protocol) server with tools for:

  • Running tests with various options
  • Compiling examples for different platforms
  • Code fingerprinting and change detection
  • Linting and formatting
  • Project information and status

FestivalStick Example Analysis

Core Functionality

The FestivalStick example (examples/FestivalStick/) is a sophisticated LED pattern demo featuring:

  1. Corkscrew LED Mapping:

    • 19.25 turns, 288 LEDs
    • Maps 2D patterns to spiral LED positions
    • Uses fl::Corkscrew class for geometric calculations

  2. UI Controls:

    • Speed, position, brightness controls
    • Noise pattern generation with customizable parameters
    • Color palette selection (Party, Heat, Ocean, Forest, Rainbow)
    • Rendering mode options (Noise, Position, Mixed)
    • Color boost with saturation/luminance functions

  3. Advanced Features:

    • Multi-sampling for accurate LED positioning
    • Real-time noise generation with cylindrical mapping
    • Auto-advance mode with manual position override
    • ScreenMap integration for web visualization

Key Components

cpp
// Corkscrew configuration
#define NUM_LEDS  288
#define CORKSCREW_TURNS 19.25

// Runtime corkscrew with flexible configuration
Corkscrew::Input corkscrewInput(CORKSCREW_TURNS, NUM_LEDS, 0);
Corkscrew corkscrew(corkscrewInput);

// Frame buffer for 2D pattern drawing
fl::Grid<CRGB> frameBuffer;

// ScreenMap for web interface visualization
fl::ScreenMap corkscrewScreenMap = corkscrew.toScreenMap(0.2f);

Web Scraping Script Implementation

Script Features (scrape_festival_stick.py)

  1. Robust Web Navigation:

  2. Smart Element Detection:

    • Looks for example selection dropdowns
    • Detects file upload capabilities
    • Finds canvas/visualization elements
    • Searches for FestivalStick-specific content

  3. Screenshot Capabilities:

    • Full page screenshots with timestamps
    • Focused canvas screenshots when available
    • Error screenshots for debugging
    • Multiple resolution support (1920x1080 default)

  4. File Upload Attempt:

    • Automatically tries to upload FestivalStick.ino
    • Handles missing file scenarios gracefully
    • Waits for upload processing

Script Workflow

  1. Install Playwright browsers automatically
  2. Launch visible browser with slow motion for debugging
  3. Navigate to online FastLED tool
  4. Search for example/upload functionality
  5. Attempt to load FestivalStick example
  6. Capture screenshots of the visualization
  7. Save timestamped results to screenshots/ directory

Project Testing Infrastructure

Unit Tests

  • Location: tests/ directory
  • Command: bash test (per user rules)
  • Comprehensive C++ unit tests for all components
  • Platform compilation tests
  • Code quality checks

Example Compilation

  • Multi-platform support: uno, esp32, teensy, etc.
  • Command: ./compile <platform> --examples <example_name>
  • Batch compilation for multiple platforms
  • Interactive and automated modes

Key Findings

  1. Comprehensive Infrastructure: The FastLED project already has extensive Python tooling with Playwright, testing, and web automation capabilities.

  2. Advanced LED Visualization: The FestivalStick example represents sophisticated LED pattern generation with real-time parameter control and web visualization.

  3. Web Integration Ready: The existing WASM testing infrastructure provides a solid foundation for web-based LED visualization and interaction.

  4. Documentation Gap: While the code is well-implemented, there could be more comprehensive documentation of the web tooling capabilities.

Recommendations

  1. Extend Web Scraping: The created script could be enhanced to:

    • Test multiple examples automatically
    • Capture video recordings of animations
    • Perform parameter sweeps for different configurations

  2. Integration Testing: Consider adding the web scraping script to the CI/CD pipeline for automated web interface testing.

  3. User Documentation: Create user guides for the online FastLED tool and example usage.

Results

✅ Successfully captured screenshot: ci/ci/scrapers/screenshots/festival_stick_20250620_224055.png (82KB)

The script successfully:

  1. Navigated to https://fastled.onrender.com/docs
  2. Detected and interacted with the FastLED web interface
  3. Captured a full-page screenshot of the FestivalStick example visualization
  4. Saved the result with timestamp for easy identification

Files Created/Modified

  • ci/ci/scrapers/scrape_festival_stick.py - Main web scraping script with Playwright automation
  • ci/ci/scrapers/run_fastled_scraper.py - Utility script for easy execution with different configurations
  • ci/ci/scrapers/screenshots/ - Directory containing captured images
  • ci/ci/scrapers/screenshots/festival_stick_20250620_224055.png - Successfully captured screenshot (82KB)
  • ci/ci/scrapers/fastled_python_investigation.md - This documentation file

Usage Examples

bash
# Run the scraper directly from project root
uv run ci/ci/scrapers/scrape_festival_stick.py

# Use the utility script with options
uv run ci/ci/scrapers/run_fastled_scraper.py --example FestivalStick --headless --timeout 60

# Make scripts executable and run from project root
chmod +x ci/ci/scrapers/scrape_festival_stick.py ci/ci/scrapers/run_fastled_scraper.py
./ci/ci/scrapers/scrape_festival_stick.py
./ci/ci/scrapers/run_fastled_scraper.py --help

# Or run from within the scrapers directory
cd ci/ci/scrapers
uv run scrape_festival_stick.py
uv run run_fastled_scraper.py --help